These days, remote accessibility is the very key to maintaining a stable network that spans a city, region, country, or the globe. One of the somewhat neglected areas for remote management, however, is at the power source. In some failure scenarios, the only way to recover functionality from a failed server, switch, or router is with the good old power cycle. Unfortunately, there are many instances where this requires someone to actually flip the power switch or even unplug a device in order to perform the hardest of resets. That’s where managed PDUs (power distribution units) can come in very, very handy.

Switchable PDUs have been around for a while and are made by many vendors. Generally speaking, they offer little in the way of configuration and features, since their only goal is to provide the ability to switch the outlet on and off. They can be serially controller or offer an Ethernet interface for telnet, SSH, or Web access. Raritan’s brand-new PX line of managed PDUs offers Web access, but with a surprising array of features.

Deep powerIn the lab, I tested the PX PCR8-15, a 1U/0U convertible unit. It’s rather deep -- far deeper than a traditional PDU -- and offers eight switchable outlets. In addition to these outlets, it has an LED power meter at the rear, and serial, Ethernet, and Feature ports on the front. Nominally, it works like a glorified power strip; you plug it into a power source, and plug other devices into the outlets on the back. That’s where the comparisons to a power strip stop, and the manageability of the PX line becomes clear.

Configuration of the PX PCR8-15 was straightforward: Plug a serial console into the serial jack, run a terminal emulator, and set some baseline configuration parameters such as a static IP address, or DHCP. The rest of the configuration can be performed via the Web interface. There’s also an SSH interface available, and all communication is encrypted with 256-bit AES (Advanced Encryption Standard).

The Web interface looks and feels exactly like the more recent KVM products from Raritan, which will all but eliminate the learning curve for those already using recent Raritan Dominion KVM-over-IP switches. The Web interface offers a significant range of options and features, from NTP (Network Time Protocol) time synchronization, LDAP and RADIUS authentication, and full SNMP poll/trap support to automated e-mail alerts, configurable voltage alert ranges per outlet, and with optional sensor modules, even humidity and temperature probes and reporting.

More than just electricityThis is where it gets interesting. With the optional temperature and humidity probes, configurable actions are possible. For instance, if the temperature reading from a probe eclipses a specified range, it’s possible to send an SNMP trap, fire off an e-mail, and turn one or more outlets on or off. This could be used in a wide variety of applications, such as powering on a small backup AC unit or powering down the same if the temperature drops too low. Obviously, anything that uses AC power can be controlled in this way.

Each outlet can be controlled individually, and set to on or off, as well as to cycle power with a specified wait state between the off and on cycle. Outlets can be grouped together, and authorized users can be presented with only the outlets or groups of outlets they can control, offering fine-grained authorization, even integrated with Active Directory, OpenLDAP, or RADIUS authentication. Local authentication is also available. The LDAP configuration is fairly straightforward for anyone versed in the protocol, but for those without that knowledge, it may prove a bit difficult.

I’m currently running several servers from the PX, and am able to get current power requirements for each power supply on each server with a click or two. With full SNMP support, that outlet status and power utilization data can be passed to telemetry applications for trend analysis and external monitoring. Also, the PX line can integrate with Raritan KVM-over-IP solutions.

A remote powerhouseThe PX line comes in an array of configurations, from the eight-outlet model I tested to 20-outlet versions, and is available in IEC (International Electrotechnical Commission) and NEMA (National Electrical Manufacturers Association) outlet arrays from NEMA 5-15R to NEMA L6-30P, supporting up to 30 amps at 230 volts. The higher-end models have their own on-board circuit breakers instead of fuses as well.

In short, the array of options and configuration parameters available in the PX is staggering for a PDU. The cost is far higher than a run-of-the-mill power strip or rack-mount PDU, but if I were building a remote site that wouldn’t have an admin present, I’d feel far better knowing that I could exercise this level of control over the hardware at that site.